The present invention relates to air conditioners, and more particularly to an automotive air conditioner compressor clutch and method wherein the engagement and disengagement of the air conditioner clutch are momentary events with no current being required to maintain the on and off state of the clutch.
The use of air conditioners in vehicles has become so widespread that almost all vehicles, and particularly full size and luxury automobiles, are now manufactured with an air conditioner as standard equipment. In many vehicles the air conditioner is automatically controlled to keep the cabin at a constant temperature. In some instances, the temperature can even be controlled to provide different areas of the vehicle cabin with different temperatures.
Typically, the air conditioner unit cools air entering the air conditioning unit from outside the vehicle or from inside the vehicle and then introduces the cooled air into the vehicle cabin through the various air ducts generally located on the dash board of the vehicle.
The air conditioner is composed mainly of an air conditioner drive source, a compressor, a condenser, an expansion valve, and an evaporator unit. The refrigerant circulating circuit is formed by connecting each component with refrigerant piping. For example, the compressor is connected to the engine as a drive source via a compressor clutch. The compressor compresses a low temperature and low pressure gas refrigerant gasified by the evaporator, and supplies the gas to the condenser as a high temperature and high pressure gas refrigerant. The condenser cools and condenses the high temperature and high pressure gas refrigerant. The refrigerant liquefied by the condenser is separated into gas and liquid and then sent to the expansion valve as a high temperature and high pressure liquid. The expansion valve decompresses and expands the high temperature and high pressure liquid to give a low temperature and low pressure liquid refrigerant which is then sent to the evaporator to complete the refrigerating cycle.
Since the air conditioner compressor in a conventional vehicle air conditioner is driven using the engine as the drive source, the capacity of the air conditioner varies depending upon the particular vehicle engine and RPM generated by the engine. Given that the cooling capacity of the refrigerant cycle increases substantially linearly in proportion to the RPM of the engine, the cooling capacity in many cases may exceed the demand on the air conditioner side. Therefore, with a conventional vehicular air conditioner, the cooling capacity is adjusted by engaging and disengaging the compressor clutch.
Current air conditioners are belt driven and when engaged, current is applied to a stationary electromagnetic coil attached to the compressor. While the clutch is engaged, the coil typically uses from about 3 to 5 amperes which, for a 12.5 volt system, amount to about 38 to 63 watts of energy steadily being consumed, causing a needless waste of energy. Therefore, it is an object of this invention to provide a momentary engaging and disengaging vehicle air conditioner clutch which drastically conserves energy and improves fuel economy.
The electrically actuated air conditioner clutch of the invention includes a clutch hub plate, latching solenoids, locking solenoids, an intermediate latch plate assembly, a latch plate spring, a belt driven pulley, a stationary coil, a pulley bearing, a latch plate bearing and a latch plate spring bearing. Generally, the air conditioner clutch of the invention is only slightly larger than conventional air conditioner clutches and it can use come of the same technology as a conventional clutch.
In accordance with the present invention, almost all of the electrical energy consumed in operating a vehicular air conditioner can be conserved with dramatic improvement in fuel economy, by momentary engagement and disengagement of the air conditioner clutch, with no current being required to maintain the on or off status of the clutch.
Assuming that the air conditioner clutch is on 30% of the time a car is driving, that the average vehicle mileage is 15,000 miles per year, that the average speed is 40 mph, that the average clutch current is 4 amperes, that there are 60 million cars with air conditioners operational in this country, then a total of 338,000 megawatt hours of electricity could be conserved annually. Since engine-driven alternators are only about 60-70% efficient, and that the engines themselves are only 20-40% efficient, a significant amount of gasoline could be saved with this device.